This invention relates generally to road construction and maintenance apparatus, and more specifically relates to a system for working or generally cutting into the surface of a road, that is, to produce cavities or openings in the pavement surface for various purposes, among them, the installation of reflectors, the formation of rumble strips in the road surface, the boring of holes in the road surface, the cutting of a striping, the milling of potholes or generally to otherwise physically affect the road surface.
There are many operations that are needed to be performed through working or in some way cutting into or affecting the surface of a road. For example, light reflective lane and border markers have come into ever increasing use on modem roads and highways. These well-known devices are installed in the pavement at spaced intervals extending in the direction of vehicular travel, so that a motorist traveling under darkened or inclement weather conditions may readily perceive the thereby defined lanes and/or borders of the roadway.
An example of the type of reflective device which is commonly used for the above purposes may be found in U.S. Pat. No. 4,174,184. Such device includes a pair of parallel elongated, laterally spaced apart keel members and an intervening portion having an arcuate part-cylindrical convex bottom portion, and an upper portion which receives a reflector assembly. The 4,174,184 patent also discloses a typical type of apparatus which can be used to form cavities in the road surface for receiving markers of the type discussed. Such apparatus includes a plurality of circular cutting or milling blades mounted on a common shaft. The outer blades are of an enlarged diameter as compared to the inner blades so that a cut can be formed in the road for matching the bottom shape of the marker. The shaft is in turn mounted on a wheeled cart that is towed to the location of each cut, where the cart is positioned so that the resulting cavity is at the desired locale for the emplaced marker. The assembly of rotatable circular blades (powered by an internal combustion engine, or hydraulic motor or the like) is placed in initial tangential contract with the road surface, and as it rotates controllably descends to the desired depth of cut. Because of this descending action, the assembly is sometimes referred to as a xe2x80x9cplunge sawxe2x80x9d, a term which at times will be used in the present specification.
Particularly in view of increased interest and awareness in road safety measures, the need for installing large numbers of the foregoing road reflectors has risen greatly. This is not to even mention the need to reinstall new reflective markers to replace or augment those which have become damaged as a result of normal weathering and wear and tear, particularly where extensive snow plowing of the road surface is a factor. While towed carts and the like are quite suitable for providing small numbers of installations, they do not lend themselves to large scale activities. The use of such rudimentary apparatus in turn leads to excessive installation costs for the many road building and installation agencies which seek to exploit the many safety advantages of the in-road installed type of light reflectors.
In several instances apparatus have been disclosed which endeavor to alleviate the disadvantages of simple towed and similar devices by providing automated plunge saws and the like which are mounted to a truck or similar vehicle. A very simple arrangement of this type is shown in U.S. Pat. No. 4,797,025, where a self-propelled cart carries a series of rotating blades to cut desired pavement slots. The blade drive shaft is powered by an hydraulic motor, and manually adjustable means enable the operator to set the depth of cut.
In U.S. Pat. No. 4,463,989 a portable road cutting machine is disclosed which is mounted on the forward end of a conventional truck body. The apparatus incorporates many hydraulic components, such as a large hydraulic reservoir, hydraulic lines and electronic hydraulic valves.
In U.S. Pat. No. 5,421,669, a further machine is disclosed for producing cavities in a roadway surface for installation of markers. The machine is mounted on a support base forming part of a powered vehicle that can be driven on the roadway surface where the road markers are to be installed. As in the 4,463,989 patent, heavy reliance is placed on numerous hydraulic components. Malfunctioning of such components can occur all too easily, e.g. a valve may remain open or closed, which can cause serious damage to the equipment or even the operator. Furthermore, in both of these truck associated systems the apparatus is so intimately connected with the vehicular carrier that dismantling of the system is a very complex and time-consuming task.
As examples of other functions that work or in some way affect the surface of a road, there is often formed in road surfaces, a series of grooves, commonly referred to as rumble strips, and which are formed by the use of an specially constructed apparatus, one of which is shown and described in U.S. Pat. No. 5,094,565 where a cutting tool is used having a plurality of cutting heads that can be used to form the rumble strip. As can be seen in that patent, a particular machine is dedicated to the formation of the rumble grooves and which forms a plurality of grooves simultaneously by milling the groves into the road surface.
As a further example of a road working function and apparatus, various boring machines are currently used to work the surface of a road and may be used to simply bore holes of a desired size to install different styles of reflectors and the like or can be used for the preparation of potholes so that the potholes are bored out to receive and hold the fresh asphalt in the alleviation of the pothole.
Now in accordance with the present invention, a system is provided for working the surface of a road to carry out variety of the aforementioned functions to that road, including the installation of reflectors, the formation of rumble strips, the boring of holes, cutting of line striping, pot hole milling by or for a variety of other functions that cut or work the road surface where the working apparatus requires some vertical adjustment to determine the desired depth of penetration. The system is defined in combination with a vehicle having a motor powered vertically movable rear lift gate which, in use, defines a vertically displaceable substantially horizontal platform. The particular rotating road working apparatus is secured to the upward facing surface of the lift gate with the apparatus itself being mounted on a rotatable drive shaft extending laterally of the gate. In one of the various embodiments, a series of cutting blades can be functionally connected to the rotatable drive shaft, and the cutting blades at least partially projecting below the bottom surface of the lift gate, whereby with the gate in a lowered position, the saw blades can engage the surface of the road on which the vehicle resides. In an alternative embodiment, the rotatable drive shaft may be connected to a differential coupling so that the horizontal rotating shaft can be converted to a vertical rotating shaft and that apparatus used to bore holes in the surface of the road or to mill the asphalt in the excavation of potholes. In any instance, a motor means is secured to the upper surface of the gate, and is connected to power the drive shaft; and means are provided to selectively adjust the vertical position of the lift gate with respect to the surface of said road, to thereby control the depth of cut and thus the degree of excavation produced by the particular road working apparatus.